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Supersaturated Diazonium salt causes Fatality

The Incident

A quantity of a diazonium chloride compound detonated, killing the operator
and injuring another employee

The investigation

The process was a standard aqueous HCL diazotization with sodium nitrite,
the diazonium slat remains in solution during the process. Prior to transfer
to the coupling vessel, the batch is screened to remove small quantities of black
residue.

On this occasion it was observed that the screen contained a large quantity
of white crystalline solid. This was transferred to a coracle during which
time the material detonated.

This process had been operated for years without incident and on this occasion
no deviations from the normal process occurred.

It was eventually discovered that the process had been running "super-saturated"
for years undetected and for some reason or other on this occasion the diazonium
chloride salt crashed out of solution.

Follow Up

Since this incident a safe test for supersaturation has been devised.
This test is described on a separate page - click here